Work feeding mechanism for sewing machine



June 30, 1959 M R. w. WINBERG 2,

WORK FEEDING MECHANISM FOR SEWING MACHINE 2 Sheets-Sheet 1 Filed Feb; 11, 1957 INV ENT0R. ,PAGNAR "W. n m/aiks Arr-Mm? June 30, 1959 R. w. WINBERG WORK FEEDING MECHANISM FOR SEWING MACHINE Filed Feb. 11, 1957 2 Sheets-Shae FIGS.

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United States Patent WORK FEEDING .MECHANISM FOR SEWING MACHINE Ragnar W. Winberg, Floral Park, N.Y.

Application February 11, 1957, Serial No. 639,463

9 Claims. (Cl. 112-211) The present invention relates generally to work-feeding mechanisms for sewing machines, and in particular to an improved bottom feeder for a conventional sewing machine. This is a continuation in part of my earlier filed application Serial No. 597,228 of July 11, 1956, entitled Rotary Feeder.

The well known sewing machine, which is most commonly employed for commercial and industrial applications, includes a feed bed over which the material assembly passes, and an oscillating feed dog below the feed bed and adapted to move through a four motion cycle. The feed dog advances the assembly to be stitched along a feed or stitching path in relation to a reciprocating needle of the machine and the spring biased presser foot which overlies the assembly and coacts with the feed dog.

In recent times, synthetic threads have become more popular and the standard sewing machines have been; found to exhibit pronounced shortcomings and disadvantages when stitching with such threads and with assemblies of synthetic fabrics. Probably, the most trouble. some difficulty is that of obtaining a substantially flat, ucker-free seam and the requisite feeding action without marking the fabric or otherwise causing distortion.

Illustrative of the serious problems which have been encountered is the attempt to provideflat and essentially ucker-free seams when using a needle or top thread and a bottom thread of nylon or nylon blends; Stitching with the conventional machine having the. standard bottom feeding accessory results in puckering or gathering along the seam and marking of the fabric, particularly when using such fragile materials as tafetta and bengaline.

I have found that the operation of a standard com mercial sewing machine may bematerially improved by the replacement of'the conventional four-motion feed dogrwith my improved bottom conveyor means sym metrically associated with the needle andcooperating with, the normal presser foot to advance the assembly to be stitched past the needle. The bottom conveyor means, advantageously in the form of side by side belts,,extends fore and aft of the needle and assures uniform advance of the material past the needle, either on an intermittent or continuous basis and does not exhibit a disturbing effect on the material assembly. A still further improvernent in the operation occurs when the conventional presser foot is replaced by one having a larger area contact with the bottom conveyor and the bottom conveyor is constructed to provide yieldable work-contacting surfaces which are continuously in contact with the under side of the material assembly to be advancedpast the needle and is driven either intermittently or continuously.v In accordance with an illustrative'embodiment of the present invention, the bottom feeder attachment is used with a sewing machine of the type having a throat plate formed with a needle hole, a presser foot overlying the throat plate, and aneedle movable into and out of theneedle hole and forming successive stitches in the material assembly, as is well understood in the sewing machine art. The attachment comprises a pair of conveyor belts fabricated of yieldable elastomer material disposed symmetricallyinrelation to the needle and cooperating with ice,

the presser foot for advancing the material past the needle. The belts are each mounted to move in a confined path having a traverse over the throat plate and lengthwise beneath the presser foot and past the needle. A drive is operatively connected to the belt for moving the belts in unison.

The above brief description as well as further objects, features and advantages of the present invention will be best understood by reference to the following detailed description of a presently preferred, but illustrative embodiment of the invention as applied to a conventional sewing machine, when taken in conjunction with the accompanying drawings, wherein;

Fig. l is a plan view of a sewing machine embodying an improved bottom feeding attachment in accordance with the present invention;

Fig. 2 is a plan view on an enlarged scale of the throat plate region of the feed bed of the sewing machine shown in Fig. l, with the large area contact of the presser foot with the improved bottom feeder being illustrated by the dot-dash lines;

Fig. 3 is a sectional view taken substantially along the line 3-3 of Fig. 2 and looking in the direction of the arrows;

Fig. 4 is a sectional view taken substantially along the line 4-4 of Fig. 2 and looking in the direction of the arrows, with parts broken away and sectioned for clarity; Fig. 5 is a side elevational view taken from the left side of Fig. 1 and with parts broken away and sectioned showing the details of the improved bottom feeder of the present invention as incorporated into the conventional sewing machine, said view being taken substantially along the line 5-5 of Fig. 2;

Fig. 6 is the sectional view taken substantially along the line 6-6 of Fig. 2 and looking in the direction of the arrows;

Fig. 7 is a fragmentary sectional view taken along the line 7-7 of Fig. 2 illustrating the relationship of the needle, the presser foot and the improved bottom feeder of the present invention;

Fig. 8 is a perspective view of a portion of the improved throat plate employed in conjunction with the bottom feeder, the conveying belts being removed for the sake of clarity;

Fig. 9 is a side elevational view similar to the showing of Fig. 5, but showing a modified arrangement for intermittently driving the improved bottom feeder attachrnent of the present invention; and

Fig. 10 is a fragmentary plan view of a throat plate of a still further modification of the present invention.

Referring now specifically to the drawings, the numeral 10 generally designates a conventional sewing machine which includes a feed bed 12, a machine body 14 from one end of which rises a hollow standard supporting a horizontally extending arm 16 which terminates in an, upright head 18 overhanging the feed bed or base 12 of the machine in the region of the throat plate 20. Extending longitudinally within the horizontal arm 16 is a drive shaft (not shown) which is coupled to the drive motor (not shown) by a belt and pulley coupling 22 out-- wardly of the hand wheel 24 of the machine. Within the upright head 18 of the machine is supported a vertically movable presser foot bar 26 which is spring biased erse of the main shaft within the sewing machine. Appropriate coordinated mechanisms are arranged to drive the needle foot bar 32 and to operate the hook and bobbin mechanism within the machine, as is well understood in the art. The details of the sewing machine are known and accordingly further description will be dispensed with.

In accordance with the present invention, the throat plate 20 of the sewing machtine is formed with a pair of channels 36, 38 arranged symmetrically of the needle hole 40 and to the vertical plane occupied by the needle 34 during successive stitch-forming strokes. Extending fore and aft of the needle hole 40, the throat plate is formed with integral and substantially triangular shaped wedge members 42, 44. The apices 42a, 44a of the wedge members 42, 44 lie substantially in the vertical plane of symmetry of the channels 36, 38.

A pair of endless and side by side belts 46, 48 are mounted below the throat plate 20 and are confined to traverse a prescribed path with successive portions of said belts 46, 48 traversing the channels 36, 38 from a location forwardly of the needle 34 past the needle and to a location rearwardly of the needle. The belts 46, 48 are fabricated of any appropriate natural or synthetic elastomer material and are of a resiliency selected to provide a cushioned bottom feeder for the sewing machine. As seen best in Fig. 7, the depth of the respective channels 36, 38 for the belts 46, 48 is selected so that the work engaging or contacting faces 46a, 48a of the belts lie in a plane slightly above the plane occupied by the top face 20a of the throat plate 20. As may be best appreciated by inspecting Fig. 2, the wedge or parting members 42, 44 fore and aft of the needle hole 40 are effective to separate the belts 46, 48, which are in contiguous and touching relation, as the belts pass the needle hole 40 whereby the needle 34 is free to operate in the needle hole 40 without binding against the adjacent sides of the belt 46, 48.

The guiding arrangement for mounting the belts 46, 48 will now be described in detail. This guiding arrangement includes a number of guiding rollers, to wit' a front top guiding roller 50, a rear top guiding roller 52, a bottom front guiding roller 54 and a rear bottom guiding and driving roller 56 (see Fig. 6). The rollers 50, 52, 54 and 56 are each of substantially identical construction and accordingly it will suffice to describe only one in detail. For example, the roller 50 includes a body proper 5011 (see Fig. 6) and opposed guide flanges 50b and 500 (see Fig. 3) at opposite ends of the body to preclude sidewise displacement of the belts 46, 48. The front top guiding roller 50 lies below and extends into a transverse slot 58 provided in the throat plate 20 adjacent the forward ends of the channels 36, 38 and is carried on an axle or pin 60 journaled on opposed depending brackets 62, 64 supported beneath the feed bed or table 12 of the machine. The rear top roller 52 is disposed below and extends into a transverse slot 66 pro-. vided in the throat plate at the rearward ends of the channels 36, 38 and is carried on an axle or pin 68 which is journaled between depending upstanding arms 70, 72 carried beneath the feed bed 12. Most conveniently, and as seen best in Fig. 5, the throat plate 20 and the respective depending brackets 62, 64 and 70, 72 may be a one-piece assembly which is mounted on the feed bed as a replacement for the conventional throat plate whereby it is not necessary to modify the construction of the machine proper except for said replacement.

By properly locating the guide rollers 50, 52 in relation to the top reference face 20a of the throat plate 20, it is possible to bring successive portions of the belts 46, 48 into contact with the work or assembly to be stitched, which has been generally designated by the reference character W in Fig. 5, with the work-contacting faces 46a, 48a slightly above the plane of the top face of the feed bed and the throat plate 20.

The bottom front guiding roller 54 is supported by a pivoted spring-biased mount whereby the conveyor belts 46, 48 are tensioned. The construction for mounting the bottom front guiding roller 54 may be best appreciated by reference to Figs. 3, 5 and 6 wherein it is seen that the brackets 62, 64 pivotally support respective arms 74, 76 which arms are mounted on the pivots 78, 80. Extending between the arms 74, 76 is the roller 54 which is carried on an appropriate pin or shaft 82 having its opposite ends journaled in the arms 74, 76. The front bottom guiding roller 54 is urged away from the rear bottom driving and guiding roller 56 by the coil springs 84, 86 which are mounted on the pivots 78, respectively and each have one end 84a, 86a anchored on the depending brackets 62, 64 and having the other end 84b, 86b operatively connected to the arms 74, 76 at the pin or shaft 82.

The rear bottom guiding and driving roller 56, which is of somewhat larger diameter than the rollers 50, 52, 54, is mounted on a shaft or axle 88 which extends between the brackets 70, 72 which brackets are of a length substantially equal to the overall length of the bracket and arm pairs 62, 74 and 64, 76.

As seen best in Figs. 5 and 6, the mounting and guiding arrangement for the conveyor belts 46, 48 is constructed to allow sufiicient clearance space for the hook and bobbin mechanisms, generally designated by the reference numeral 90, which occupy the region immediately beneath the throat plate and intermediate the four posts or brackets 62, 64 and 70, 72. Further the arrangement is such that it can be accommodated into the available space in this sewing machine without interfering with the operating mechanisms of the machine, it being recalled that the conventional four-motion feed dog and directly associated supporting parts have been removed. In this connection, the front rocker shaft 92 extending lengthwise of the feed bed and arranged forwardly of the belt guiding arrangement does not have to be removed and is not interfered with. The rocker shaft 92 would normally impart the up and down motion to the conventional feed dog. Similarly, the rear rocker shaft 94 arranged rearwardly of the guiding arrangement need not be removed, this shaft being present in the standard machine to impart the requisite back and forth movement to the conventional feed dog.

In order to provide the required drive to the conveyor belts 46, 48, a gear 96 is connected to the driving and guiding roller 56 at its axle 88 and this gear is connected to a driving worm 98 and via a flexible cable 100 to the main drive of the sewing machine. The cable 100 is contained in a sheath 102 and is driven by a belt and pulley coupling 22 connected to the drive shaft of the machine which has provisions for speed selection. The flexible coupling shaft 100 is effective to impart drive to the gear 96 for advancing successive portions of the belts 46, 48 past the needle as a function of the speed selection means incorporated into the belt and pulley coupling 104. Although the drive which advances the work past the needle is substantially continuous, the feed is rendered somewhat intermittent by the action of the needle entering the work which causes the coupling shaft to be periodically subjected to torsional loading. For further details of the construction and operation of this illustrative system for imparting stepwise drive to the belts 46, 48 reference may be made to my United States Patent No. 2,777,409 of January 15, 1957.

A typical cycle of operation will be described in order to facilitate a more thorough understanding of the present invention:

The speed selection arrangement 22 is adjusted to assure that the proper stepwise movement will be imparted to the belts 46, 48. Thereupon the work W is advanced in the conventional fashion beneath the presser foot 28 and when engaged therebeneath the large work-area con, tact, designated by the letter A in Fig. 2 and enclosed the dot-dash line, will provide a feed zone for the work which extends for a substantial distance fore and aft of the needle and at each side of the needle. During each successive advance of the work as a function of the intermittent drive of the conveyor belts 46, 48, the work W is bottom fed with its top face in contact with the large area presser foot 28. As such, the work is not disturbed yet is supported during its advance in relation to the needle 34. In effect there is provided a uniform feed zone for a substantial region fore and aft of and at each side of the needle in which uniform feed zone there are no disturbing influences on the work itself. A more trouble free operation is thus realized. This substantial improvement in bottom feeding may be more fully appreciated by considering the disturbing influences on the work with a conventional feed dog which in its fourmotion feed path during each stitch-forming stroke (during each rotation of the main shaft) comes into contact with the work, attempts to move the work along and is withdrawn from contact with the work. The present improved construction is maintained continuously in contact with the work and as such during the passage of the work through the critical regions around the needle achieves an isolation of such regions from disturbing influences.

The slight spreading or parting of the belts 46, 48 as a result of the function of the wedge or parting members 42, 44 does not disturb the operation of the stitching mechanism. The slight transverse tensioning of the material does not appreciably eifect the characters of the stitching or interfere with the desired operation.

Reference will now be made to Fig. 9 which shows a modified arrangement for imparting drive to the belts 46, 48. In lieu of the use of a gear 96 and the engaging worm 98 with the flexible coupling 100 to the drive shaft of the machine as illustrated in the main embodiment, this further arrangement contemplates the drive of the belt 46, 48 from the rear rocker shaft 94 of the sewing machine. This rear rocker shaft is normally connected to the feed dog and is effective to move the feed-dog through the forward feeding stroke and the rearward return stroke along with the front rocker shaft '92 which imparts the up and down motion to the feed dog. In the alternative arrangement of Fig. 1, a conventional one-way clutch 100 is connected to the shaft or axle 88 of the driving and guiding roller (not shown) and is coupled via an adjustable length coupling 102 to a crank 104 fixed to the rear rocker shaft 94. The one-way clutch, which is of a conventional spring-ball type, includes a driven member 106 connected to the shaft or axle 88', a drive member 108, and a number of spring-biased balls 110 seated therebetween and eifective to couple motion from the driving member 108 to the driven member 106 in response to counter clockwise movement of the driving member 108 about the axle or shaft 88. The construction of this type of clutch is well known in the art. In response to clockwise movement, no motion is imparted to the shaft 88. The adjustable-length coupling includes a coupling bar 111 having its opposite ends threaded and engaged in yokes 112, 114, the yoke 112 being pivotally connected to the driving member 108 and the yoke 114 being selectively adjustable along a radially-extending slot 116 provided in the crank or rocker arm 104. As is well understood, the stroke imparted to the drive member 108 of the coupling 102 may be selectively adjusted by varying the position of the yoke 114 in the slot 116 relative to the rocker shaft or crank shaft 94.

In Fig. IO there is shown a modified throat plate 20' which may be employed with the bottom feeding mechanism illustrated in Figs. 1 to 8 inclusive, with the drive in said figures, or the alternative drive of Fig. 9. The modified throat plate includes wedge or parting members 120, 122 arranged forwardly and rearwardly of the needle hole 124 and disposed symmetrically in relation to the or feeding path. As seen in Fig. 10, the wedge or parting members 120, 122 are of progressively increasing cross-section whereby the belts 46, 48 are progressively spread apart in their travel from the location forwardly of the needle hole 124 to a location rearwardly of the needle hole 124. This progressive spreading action laterally tensions the material as it passes through the stitching zone. This tension, which is tranverse or lateral to the stitch line, has been found to be helpful in placing the thread into the material or fabric so that the stitched assembly will have a flat seam with little puckering. Further details concerningthe benefit of laterally tensioning the material as it passes through the stitching zone may be found in my copending application Serial No. 597,228 which discloses a pair of rotary feed wheels as a top feeder for lateral tensioning.

The use of the improved bottom feeder of the present invention does not interfere with the normal operation of the sewing machine and may be incorporated onto almost any conventional standard sewing machine by merely replacing the standard throat plate with the modified throat plate and by removing the feed dog and associated supporting mechanisms to provide adequate clearance space for the present bottom feeder. The drive may be imparted to the bottom feeder either from the mechanisms used in association with the conventional feed dog or by connection to the main drive of the sewing machine by the flexible coupling described herein.

Although I have only described several embodiments of the present invention, a range of alternatives, modifications, omissions and additions should be readily apparent to those skilled in the art. It is appropriate that the appended claims should be accorded a latitude of interpretation consistent with the spirit and scope of the invention; and in some instances some features of the invention will be used withouta corresponding use of other features.

I claim:

1'. In a sewing machine, stitch-forming mechanisms including a needle, a throat plate over which material is adapted to travel, a presser foot bar, a presser foot carried on said presser foot bar, and means for advancing said material over said throat plate and beneath said presser foot bar for action thereon by said stitch-forming mechanisms, said means including a pair of endless belts disposed at opposite sides of said needle and abutting each other, means defining a prescribed path of travel for each of said belts including a course extending lengthwise of and beneath said presser foot, wedge means interposed between said belts in the region of said needle and arranged to spread said belts apart to provide clearance between said belts for operation of said needle, said wedge means having a needle hole formed therein, said belts when driven cooperating wtih said presser'foot for advancing said material past said needle, and a drive for said belts.

2. In a sewing machine, stitch-forming mechanisms including a needle, a throat plate over which material is adapted to travel, a presser foot bar, a presser foot carried on said presser foot bar, and means for advancing said material over said throat plate and beneath said presser foot bar for action thereon by said stitch-forming mechanisms, said means including a pair of endless belts of resilient material disposed at opposite sides of said needle and in side by side abutting relation, means defining a prescribed path of travel for each of said belts including a course extending lengthwise of and beneath said presser foot, wedge means interposed between said belts in the region of said needle and providing clearance between said belts for operation of said needle, said wedge means being integral with said throat plate and having a needle hole formed therein, said belts when driven cooperating with said presser foot for advancing said material past saidneedle, and a drive for said belts.

3. In a sewing machine, stitch-forming mechanisms including a needle, a throat plate over which material is adapted to travel, a presser foot bar, a presser foot car ried on said presser foot bar, and means for advancing said material over said throat plate and beneath said presser foot bar for action thereon by said stitch-forming mechanisms, said means including a pair of endless belts disposed at opposite sides of said needle and in side by side diverging relation in the direction of material advance, means defining a prescribed path of travel for each of said belts including a course extending lengthwise of and beneath said presser foot, means interposed between said belts in the region of said needle and having a needle hole formed therein, said belts when driven cooperating with said presser foot for advancing said material past said needle, and a drive for said belts.

4. A sewing machine comprising a main drive, a throat plate having a needle hole, a needle movable into and out of said needle hole and driven through a prescribed stitch-forming stroke by said main drive, a presser foot, means including a presser foot bar supporting said presser foot over said throat plate in position to bear against the material being stitched, said throat plate being formed with channels arranged symmetrically of said needle and extending fore and aft thereof, each of said channels terminating at its opposite ends in a through slot, a pair of endless belts arranged generally below said throat plate, means to confine each of said endless belts to traverse a prescribed path with said belts lying in the respective channels in side by side abutment at opposite sides of said needle and extending through the adjacent slots, means for spreading said belts in the region of said needle, and means operatively connected to said endless belts to drive the same whereby successive portions of said belts traverse said channels and are effective in conjunction with said presser foot to advance the material past said needle.

5. A sewing machine comprising a main drive, a throat plate having a needle hole, a needle movable into and out of said needle hole and driven through a prescribed stitch-forming stroke by said main drive, a presser foot, means including a presser foot bar supporting said presser foot over said throat plate in position to bear against the material being stitched, said throat plate being formed with channels in side by side and communicating relation, said channels being arranged symmetrically of said needle and extending fore and aft thereof, a pair of endless belts arranged generally below said throat plate, means to confine each of said endless belts to traverse a prescribed path with said belts lying in the respective channels in side by side abutment at opposite sides of said needle, means for spreading said belts in the region of said needle, and means operatively connected to said endless belts to drive the same whereby successive portions of said belts trav erse said channels and are effective in conjunction with said presser foot to advance the material past said needle.

6. A sewing machine comprising a main drive, a throat plate having a needle hole, stitch-forming mechanisms including a needle movable into and out of said needle hole and driven through a prescribed stitch-forming stroke by said main drive, a presser foot, means including a presser foot bar supporting said presser root over said throat plate in position to bear against the material being stitched, said throat plate being formed with side by side channels arranged symmetrically of said needle and extending fore and aft thereof, a pair of side by side endless belts of resilient material arranged generally below said throat plate and abutting each other, means to confine each of said endless belts to traverse a prescribed path with said belts lying in the respective channels, means for spreading said belts in the region of said needle, and intermittently operable means operatively connecting said main drive to said endless belts to drive the same in timed relation to operation of said needle, whereby successive portions of said belts traverse said channels and are effective in conjunction with saidpresser foot to advance the material stepwise past said needle.

7. A sewing machine comprising a main drive, a throat plate having a needle hole, stitch-forming mechanisms including a needle movable into and out of said needle hole and driven through a prescribed stitch-forming stroke by said main drive, a presser foot, means including a presser foot bar supporting said presser foot over said throat plate in position to bear against the material being stitched, said throat plate being formed with channels arranged symmetrically of said needle and extending fore and aft thereof, a pair of side by side endless belts mounted generally below said throat plate, means to confine each of said endless belts to traverse a prescribed path with said belts lying in the respective channels in side by side abutting relation, separating means on said throat plate formedwith said needle hole, said separating means being efiective to guide said belts apart in the region of said needle, and means operatively connected to said endless belts to advance said belts in unison whereby successive portions of said belts traverse said channels and are effective in conjunction with said presser foot to advance the material past said needle.

8. A sewing machine comprising a main drive, a throat plate having a needle hole, stitch-forming mechanisms including a needle movable into and out of said needle hole and driven through a prescribed stitch-forming stroke by said main drive, a presser foot, means including a presser foot bar supporting said presser foot over said throat plate in position to bear against the material being stitched, said throat plate being formed with parallel channels merging at their adjacent sides and arranged symmetrically of said needle, a pair of endless belts mounted generally below said throat plate, means to confine each of said endless belts to traverse a prescribed path with said belts lying in the respective channels, separating'means on said throat plate formed with said needle hole, said separating means being effective to guide said belts apart in the region of said needle, and means operatively connected to said endless belts to advance said belts in unison whereby successive portions of said belts traverse said channels and are effective in conjunction with said presser foot to advance the material past said needle. 7 9. A sewing machine comprising a main drive, a throat plate having a needle hole, stitch-forming mechanisms including a needle movable into and out of said needle hole and driven through a prescribed stitch-forming stroke by said main drive, a presser foot, means including a presser foot bar supporting said presser root over said throat plate in position to bear against the material being stitched, said throat plate being formed with channels extending fore and aft of said needles, said channels diverging outwardly rearwardly of said needle, a pair of endless belts mounted generally below said throat plate, means to confine each of said endless belts to traverse a prescribed path with said belts lying in the respective channels, separating means on said throat plate formed with said needle hole, said separating means being effective to guide said belts apart in the region of said needle, and means operatively connected to said endless belts to intermittently advance said belts in unison whereby successive portions of said belts traverse said channels and are effective in conjunction with said presser foot to advance the material past said needle.

References Cited in the file of this patent UNITED STATES PATENTS 365,956 Wilson July 5, 1887 1,661,023 Turner et al Feb. 28, 1928 2,298,665 Wesson Oct. 13, 1942 FOREIGN PATENTS 508,129 Germany Sept. 27, 1930 Mun-x. v 

